Ptolemy's theorem

Plane GeometryLet ABCD be a quadrilateral where all the vertices lie on a circle. As long as the (green) diagonals cross, ABxCD+BCxDA=ACxBD; in words, the sum of the products of the two pairs of opposite sides equals the product of the diagonals. Drag any vertex to another location on the circleComponente Curricular::Ensino Fundamental::Séries Finais::Matemátic